Chlorofluorocarbon (CFC) based chemicals have been widely use in industry in a variety of different applications including as refrigerants, aerosol propellants, blowing agents and solvents, among others. Certain CFCs, however, are suspected of depleting the Earth's ozone layer. Accordingly, more environmentally friendly substitutes have been introduced as replacements for CFCs. One example of such a substitute is 1,1,1,3,3-pentafluoropropane (HFC-245fa). HFC-245fa is recognized as having favorable physical properties for certain industrial applications, such as foam blowing agents and solvents, and therefore is considered to be a good substitute for the CFCs previously used for these applications. Unfortunately, the use of certain hydrofluorocarbons, including HFC-245fa, in industrial applications is now believed to contribute to global warming. As a result, more environmentally friendly substitutes for hydrofluorocarbons are now being sought.
The compound 1-chloro-3,3,3-trifluoropropene, also know as HCFO-1233zd or simply 1233zd, is a leading candidate for replacing HFC-245fa in some applications, including blowing agents and solvents. 1233zd has a Z-isomer and an E-isomer. Due to differences in the physical properties between these two diastereoisomers, pure 1233zd(E), pure 1233zd(Z), or certain mixtures of the two isomers may be suitable for particular applications as refrigerants, propellants, blowing agents, solvents, or for other uses.
Processes for synthesizing 1233zd are known. WO 97/24307, for example, discloses a process for preparing 1233zd via the gas-phase reaction of 1,1,1,3,3-pentachloropropane (HCC-240fa) with hydrogen fluoride (HF). This process, however, produces relatively low yields of 1233zd. U.S. Pat. No. 6,844,475 describes a liquid phase reaction of HCC-240fa with HF to produce 1233zd in higher yields. A preferred temperature range for this reaction was purported to be about 50° C. to about 120° C., with specific examples being demonstrated at 90° C. (resulting in a 1233zd yield of about 80 wt. %) and 120° C. (resulting in a 1233zd yield of over 90 wt. %). The 1233zd yield at the lower temperature is not particularly good. The yield at the higher temperature is good, but Applicants have found that operating the process at this temperature and above produces increased amounts of the Z-isomer. Accordingly, there remains a need for a process for selectively producing 1233zd(E) in high yields. This application satisfies that need among others.